Antifouling Properties of Liquid-Infused Riblets Fabricated by Direct Contactless Microfabrication

The fabrication of riblets and surfaces structured with aligned grooves, by direct contactless microfabrication (DCM), and the ability of the riblets to function as lubricant-infused surfaces, is reported. Three types of riblets are fabricated with features (width, height, and period) on the micrometric scale, and with two different UV-crosslinkable coatings. Riblets with width 10 μm, period 40 μm, and height 30 μm show high water repellence as prepared (water contact angle [WCA] 147°) and, once infused with silicone oil 10 cSt, result in water droplets rolling off the surface at tilt angles of 10°. These riblets are effective at reducing the attachment of marine bacteria, both in the as-prepared and infused form. The DCM process produces structured surfaces over large areas (10 × 10 cm²) in a few minutes and using inexpensive materials, making mechanically robust surfaces. The DCM process is scalable to the large surface areas required for marine and other applications. The low roll-off angles and the bacterial inhibition results achieved on the riblets indicate that riblets are an up-scalable and nontoxic alternative to more complicated fabricated techniques, with potential as antifouling and drag-reducing coatings.